1. Field of Technology
The present disclosure relates to vibration dampening components, and more particularly relates to vibration dampening handles for powered apparatus. Such powered apparatus include, without limitation, example, powered woodworking and metal working tools and other power tools.
2. Description of the Background of the Technology
Power tools and other powered apparatus can generate substantial vibration during operation. Power tools, for example, may include reciprocating and/or rotating tool members such as bits, discs, and belts and, as such, vibration can be exacerbated when the tool member contacts a workpiece. One specific example of a power tool including a rotating part is a hand-held grinder, which includes a rotating abrasive disk. The grinder will generate a base level of vibration when the motor is engaged and the disk is rotating, and at least the magnitude vibration will increase when the abrasive disk contacts and is abrading a workpiece.
An objective of certain prior power tool designs has been to provide handles that dampen (i.e., reduce the magnitude of) vibrations and thereby transmit a reduced level of vibrations to the hand of an operator grasping the handle. Dampening vibrations increases operator comfort and reduces hand fatigue, allowing an operator to comfortable use the power tool for extended periods. Dampening vibrations also can improve an operator's control of the power tool, which can be especially important when doing fine work such as finish work on wooden workpieces.
Certain previous attempts to address the vibration problem have focused on including in the handle some type of vibration absorbing elastic element. U.S. Pat. No. 5,365,637, for example, discloses a vibration absorbing power tool including an elongated gripping member with first and second ends and an inner bore extending along a longitudinal axis of the gripping member and opening on the first end. An elongated support member, disposed in the inner bore, extends coaxially along the longitudinal axis. Means for mounting the gripping member to a power tool is mounted at the gripping member's first end and is spaced from an end of the support member. The gripping member, which is a monolithic elastomeric body, includes a region forming a radially extending flexible flange between the support member and the mounting means. The flexible flange permits the handle to flex in a direction generally transverse to the longitudinal axis, permits slight translation of the handle along the longitudinal axis, and absorbs some part of the vibration reaching the handle.
U.S. Pat. No. 5,273,120 discloses a vibration dampening handle for a power tool including an elongated handle housing having a longitudinal axis of symmetry and a first end. A bore extends into the housing along the longitudinal axis and opens on the first end. A support member is connected to the housing and is coaxial with the longitudinal axis and extends into the bore. A hollow tubular elastic flex member is telescoped over the support member, extends into the bore, and is affixed to both the handle housing and support member. A mounting surface on the tool includes an outwardly extending apex to which the support member is connected. The handle can rock back and forth over the apex as the flex member is flexed by vibrations from the tool.
U.S. Pat. No. 5,170,532 discloses a vibration dampening power tool handle including a hollow tubular member having a bell-shaped socket at a first end. A second end of the tubular member receives a stem portion of weighted mass, which is provided to reduce the handle's resonance frequency of the handle. The bell-shaped socket includes a circumferential groove formed on its inner periphery. A vibration insulating spring element, which may be a conical steel disc or membrane, is snapped into the circumferential groove. The spring element includes a central opening into which a mounting means may be disposed and connected to the power tool. Vibrational energy from the power tool is partially dissipated by the flexing motion of the spring element.
United States Patent Application Publication No. US 2004/0016082 A1 discloses a vibration absorbing power tool handle including a hollow tubular gripping member having first and second ends and an inner bore therethrough along a longitudinal axis of the gripping member. Two cylindrical elastic members having bores therethrough are disposed within the inner bore in a spaced apart relation near the first end of the gripping member. A rigid connecting member is disposed through and connected within the bores of the elastic members so that the connecting member can translate to some degree relative to the gripping member. An end of the connecting member extends beyond the first end of the gripping member and is connected to the power tool. The rigid connecting member acts to stiffen the handle, while the elastic members couple the gripping member to the connecting member and also absorb vibration transmitted from the power tool.
Certain other prior art power tool handle designs incorporate elements channeling the vibratory movement of the handle into less problematic translational modes. U.S. Pat. No. 5,769,174, for example, discloses a vibration dampening handle including a hollow space in which first and second base members are disposed. A surface of the first base member is parallel in an “x” direction and opposes a surface of the second base member, and the two base members are spaced apart in a “z” direction perpendicular to the “x” direction. Two parallel elongate flexible (elastic) beam members are connected to and span the “z” distance between the opposed base member's surfaces. The first base member may move within the handle in a “y” direction that is perpendicular to the “x” and “z” directions, but the first base member is restrained from moving in the “x” and “z” directions. This arrangement channels a portion of the vibratory loading on the handle to the “y” direction, and little angular deflection of the beam members occurs in the “x” and “z” directions. Accordingly, the handle is said to improve operator control by absorbing relative induced motion or vibration in one preferred direction, while retaining relative stiffness in the remaining two directions, and also by restraining the handle from torsional twist.
Despite the existence of the foregoing vibration dampening arrangements, there remains a need for innovative designs for power tool handles that reduce vibrations transmitted to the operator's hand. More generally, there remains a need for innovative handle designs that reduce transmitted vibration from other types of powered apparatus to an operator's hand.